1. Field of the invention
The invention relates to a fan that includes:
a frame;
a rotor supported rotatably by this frame and having                a central hub; and        a number of substantially similar blades which are connected to this hub in angularly equidistant arrangement and extend at least more or less in radial direction, which blades have an aerodynamic form such that during rotary driving of the rotor round the axis of the hub an air displacement occurs; and        
drive means for rotatably driving the blades with the hub around the axis of the hub;
a ring to which the end zones of the blades are connected.
2. Description of Related Art
Such a fan is known, for instance from NL-A-9402191. Known are small fans for household use right up to very large fans used to ventilate enclosed spaces, for instance buildings, for air-conditioning systems, cold-storage plants, air tunnels and the like.